Method and apparatus for treating solid wastes

ABSTRACT

Waste burning means, gas treating means in communication with said waste burning means and gas separating means in communication with said gas treating means and waste burning means, said waste burning means includes a burning chamber and pressurized pyrolysis chamber, wherein burning chamber is being made such that it is capable of burning completely organic wastes thereof, whereby gas products of combustion are produced, and said pyrolysis chamber being made such that it is capable of converting plastic wastes into synthesis gases through utilization of heat from the burning chamber, heat exchanging means disposed within the burning chamber being arranged in a manner wherein water from a water source is capable of conversion into steam thereof through utilization of heat in the burning chamber, said gas treating means includes a secondary treatment chamber in communication with the burning chamber, wherein high temperature gas products of combustion coming from the burning chamber is capable of mixing with low temperature steam, said gas separating means being arranged such that the gas products mixed with steam coming from the gas treating means is capable of swirling cyclonic motion thereof, thereby allowing the lighter gases to be discharged to the atmosphere and be separated from particulates and heavier gases which are subsequently recycled and feed back into the burning chamber, and steam and synthesis gas lines provided in the waste burning means being arranged such that it is capable of introduction to the burning chamber the steam produced by the heat exchanging means and synthesis gas coming from the pyrolysis chamber.

TECHNICAL FIELD

The present invention relates generally to waste management and more particularly to a method and apparatus for treating solid wastes.

BACKGROUND OF THE INVENTION

Organic wastes, such as plastics, wood, paper, cellulose, etc., are burned in incinerators without any treatment steps that would insure environmental safety and protection. Plastic materials and other organic waste have different heating value, which react differently when burned such that exhaust gases discharged from these refuse incinerators contains minor components, such as smoke dust, hydrogen chloride, carbon monoxide, Sox, NOx, heavy metals including mercury or dioxin and furan, which are considered harmful. From the standpoint of environmental protection, it is necessary to remove these harmful substances.

Of those, dioxins have extremely strong toxicity such that collection and removal of this is extremely important. Plastics should therefore have to be reduced in gas form to achieved complete combustion along with the other gases generated by the other organic waste. This will ensure reduction to safety level the toxic gases coming from the exhaust of the incinerator.

Burning of these organic wastes requires high temperature, preferably more than 1000 degree Celsius, to facilitate combustion and elimination of toxic gases generated by such organic wastes. However, in conventional incinerators such temperature cannot be attained since it will require tremendous amount of fuel, thus rendering it to be too costly to do.

An example of incinerator of the prior art is the conventional refuse incinerator facility wherein a boiler and auxiliary burner is used. The refuse is directly burned in order to raise the temperature of the incinerator and the temperature of boiler water in the boiler. At the initial start of operation, there is already a production of low-temperature combustion gas which inflicts damage to the facility since it causes low-temperature corrosion. To solve this problem, the common practice is to discharge this combustion gas by way of a by-pass duct and stack. However, there is still the possibility that dust containing hazardous substances, such as dioxins, remaining in the incinerator and boiler. If such contamination substances are deposited and still remaining in the incinerator, there is the possibility that during the steady operation, these substances will be emitted and discharged as gaseous dioxin in the atmosphere.

Another example is an exhaust gas treating apparatus wherein the refuse is incinerated in the incinerator and then completely combusted by secondary air in a secondary combustion chamber. Ash is then discharged to the atmosphere while the exhaust gas generated as a result of the combustion of refuse in the secondary combustion chamber is subjected to heat recovery by waste heat boiler and waste heat reclaimer (pre-heater) as it flows towards a quenching reaction tower.

In the quenching reaction tower, the exhaust gas is sprayed with slaked lime slurry so that hydrogen chloride (HCL) and sulfur oxide (SOx) are removed. Smoke dust, fly ash, HCL. Sox, heavy metals and dioxins, which remains in the exhaust gas, are then removed in a bag filter. The exhaust gas after treatment is then discharge to the atmosphere.

Although the exhaust gas from an incinerator is treated with the aforementioned process, there is the possibility that dioxins cannot be reduced to the desired low concentration. Dioxins generated during incineration are almost decomposed in the secondary combustion chamber, however, it is necessary to decrease the temperature of the exhaust gas from a high temperature of about 350 to 900 degree centigrade to a low temperature during every step of the process. However, there is the tendency of dioxins regenerating at the vicinity of 300 degree centigrade during every step of the process such that the above-mentioned conventional exhaust gas treatment apparatus cannot effectively collect and removed dioxins at the desired low concentration.

SUMMARY

The primary object of the present invention is to provide a method and apparatus for treating solid wastes which can remedy the above drawbacks of the prior arts.

Another object is to provide an apparatus and method for treating solid wastes wherein the treatment includes subjecting the toxic gases generated by biodegradable waste, such as plastic, wood, paper, cellulose, etc., to high temperature and pyrolysis process to facilitate combustion of toxic gases. Pyrolysis is the process of heating fuels and other combustible elements without oxidation, this means that the thermally treated solid waste are reduced into fuel and change its phase into a gaseous form without the presence of air and oxygen. The gas product from a pyrolysis process is called synthesis gas which can be used as fuel.

The present method and apparatus further provides separating means wherein heavy gases are separated from the lighter and clean gas such that the lighter gas is safely release in the atmosphere while heavy toxic gases are diverted and recombusted.

Still another object is to provide a method and apparatus for treating solid wastes which can provide heating temperature of more than 1000 degree Celsius for combusting gases.

Yet another object is to provide a method and apparatus for treating solid wastes wherein environmentally compatible catalyst, such as pyrolytic steam injection process, is used in combination with gasification system assisted with water for high temperature burning with clean emission. Cleaner emission, since it only uses water and steam and no chemicals are used in the process.

A further object is to provide an apparatus for treating solid wastes which is very easy to operate and can be used in municipalities and barangays for their solid waste management.

Other objects and advantages of the present invention will be realized upon reading the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a sectional presentation of the burning means of the present invention,

FIG. 2 is a right side sectional view showing the burning means attached to the gas separating means of the present invention,

FIG. 3 is a rear view of the present apparatus,

FIG. 4 is a left side sectional view of the same, and

FIG. 5 is a front view of the present apparatus

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, there is shown an apparatus of treating gases of biodegradable wastes generally designated as 10 comprising waste burning means 11, gas treating means 11 a in communication with said waste burning means, and gas separating means 12 in communication with said waste burning means and gas treating means. Burning means 11 includes an organic burning chamber 13 and pressurized pyrolysis chamber 14. Organic burning chamber 13 is being made such that it is capable of burning organic wastes, such as wood, paper, cellulose and other biodegradable wastes and pressurized pyrolysis chamber 14 is capable of containing and burning thereof solid or compacted plastic wastes. A heat exchanger 15 provided within the organic burning chamber 13 and disposed above a grate member 16 provided thereof. Heat exchanging means 15 having one end in communication with a water source, such as tank 16, and the other end to a pressurized steam storage means, such as tank 17. A steam gas line 18 in communication with said steam tank 17 being arranged such that it is capable of spraying steam within the organic burning chamber and below the grate member. A pyrolysis gas line 18 in communication with the pyrolysis chamber 14 being arranged such that it is capable of introducing gas within the organic burning chamber 13. Said gas treating means includes a secondary treatment chamber 19 in communication with the burning chamber 13, wherein high temperature gas products of combustion coming from the burning chamber are treated and mixed with cold steam, thereby preventing the formation of dioxin and furan. Said gas separating means 12 is a cyclonic separator 20 in communication with the secondary treatment chamber 19, wherein the treated gases coming from the secondary treatment chamber are allowed to flow through an induced draft fan 21 provided thereof. Said cyclonic separator 20 is being made such that it is capable of providing cyclonic swirling motion to the gases in which heavy gases (toxic and unburned gases) and particulates are separated from lighter and clean gases. The heavy gases are allowed to flow back in the burning chamber for further burning while the light gases are discharged in the atmosphere. Cyclonic separator 20 is preferably a hollow chamber in communication with the secondary treatment chamber and burning chamber 13 through suitable duct means. A stack 22 provided in said hollow chamber wherein light gases are capable of discharging in the atmosphere and a gas guide means 23 disposed therein. Said guide means 23 being made in a manner wherein it is capable of allowing the gases from the secondary treatment chamber to move in a cyclonic swirling motion, thereby allowing the lighter gases to move upwardly towards the stack 22 and the heavier gases to move sidewardly towards the recycle duct D. From the recycle duct the heavy gases then flows back to the burning chamber for further heating.

The process of reducing municipal solid waste using thermal reduction through the use of combined action of plastic pyrolysis and biomass-steam gasification is designed to burn efficiently and emits a cleaner and environmentally friendly product of combustion. The thermal waste processor is a type of waste reduction that burns and reduces waste in the organic burning chamber and pyrolysis chamber.

In operation, the solid waste is segregated wherein plastic waste is contained in the pyrolysis chamber and the biomass waste is contained in the burning chamber. Biomass waste is then burned by suitable fuel as a start up until it reaches self-sustaining heat through continuous feeding of biomass waste. As the heat in the combustion chamber becomes high, the pyrolysis chamber also heats up resulting in the plastic material therein to be burned and turned into synthesis gases which is highly combustible. The pyrolysis chamber is separated from the combustion chamber 13 so that toxic gas formation will be eliminated. Organic and plastic waste has different heating value which reacts differently when burned such that plastic waste should be totally converted into gas form such that it can be utilized as fuel in combination with organic biomass fuel. During burning, the heat exchanging means in the burning chamber turns the water flowing thereof into steam which is subsequently is introduced in the burning chamber together with the synthesis gas from the pyrolysis chamber. The introduction of synthesis gas and steam in combination with the burning fuel increases the temperature in the burning chamber of up to a high temperature of 1,000 to 1,500 degree Celsius and changes the flame into plasma. While the biomass is burned completely, the product of combustion, which is high temperature gases, is allowed to flow in the secondary treatment chamber 19 wherein it is treated with cold steam to reduce its temperature and prevent the formation of dioxin and furan (toxic gas that comes from chlorine-based pilate). The treated gases is then allowed to flow in the cyclonic separator 20 where it is subjected to a swirling cyclonic motion to create a centrifugal force build up which causes the heavy gases and particulates to separate with lighter gases. The tendency of the lighter gases or clean gases is to move upwardly such that it is discharged to the atmosphere, whereby the heavy gases and particulates flows to the side of the separator where it is drawn back to the combustion chamber for further burning. 

1. A method for treating solid wastes comprising the steps of: a) Confining separately biomass wastes from plastic wastes; b) Burning the biomass wastes; c) producing steam by heat exchange through utilization of the heat produced by the burning biomass wastes; d) converting plastic wastes into synthesis gases through utilization of the heat coming from the burning chamber; e) introducing the said steam and synthesis gases to the flame of the biomass fuel such that there is an increase in temperature, thereby burning the biomass completely and produces high temperature gas products of combustion; f) treating the high temperature gas products with cold steam such that dioxin and furan formation is eliminated; g) allowing the treated gas products to undergo swirling cyclonic motion such that particulates and heavy gases are separated from lighter gases, whereby the lighter gases are discharged in the atmosphere and the particulates and heavy gases are recycled and retreated again.
 2. A method for treating solid wastes according to claim 1 wherein the temperature of the heat is about 1000 to 1500 degree Celsius.
 3. An apparatus for treating solid wastes comprising: Waste burning means, gas treating means in communication with said waste burning means and gas separating means in communication with said gas treating means and waste burning means, said waste burning means includes a burning chamber and pressurized pyrolysis chamber, wherein burning chamber is being made such that it is capable of burning completely organic wastes thereof, whereby gas products of combustion are produced, and said pyrolysis chamber being made such that it is capable of converting plastic wastes into synthesis gases through utilization of heat from the burning chamber, heat exchanging means disposed within the burning chamber being arranged in a manner wherein water from a water source is capable of conversion into steam thereof through utilization of heat in the burning chamber, said gas treating means includes a secondary treatment chamber in communication with the burning chamber, wherein high temperature gas products of combustion coming from the burning chamber is capable of mixing with low temperature steam, said gas separating means being arranged such that the gas products mixed with steam coming from the gas treating means is capable of swirling cyclonic motion thereof, thereby allowing the lighter gases to be discharged to the atmosphere and be separated from particulates and heavier gases which are subsequently recycled and feed back into the burning chamber, and steam and synthesis gas lines provided in the waste burning means being arranged such that it is capable of introduction to the burning chamber the steam produced by the heat exchanging means and synthesis gas coming from the pyrolysis chamber.
 4. An apparatus for treating solid wastes according to claim 3 wherein water storage means and steam storage means are in communication with said heat exchanging means.
 5. An apparatus for treating solid waste according to claim 3 wherein said gas separating means is a cyclonic separator having a stack for gas discharge and guide means disposed thereof, said guide means being made such that it is capable of providing swirling cyclonic motion to the gases passing thereof, such that the lighter gases are capable of moving upward and be discharged in said stack and the particulates and heavy gases are capable of returning to the burning chamber. 